IP Multimedia (IPMM) services provide a dynamic combination of voice, video, messaging, data, etc. within the same session. By growing the numbers of basic applications and the media that it is possible to combine, the number of services offered to the end users will grow, and the inter-personal communication experience will be enriched. This will lead to a new generation of personalised, rich multimedia communication services, including so-called “combinational IP Multimedia” services, which are considered in more detail below.
IP Multimedia Subsystem (IMS) is the technology defined by the Third Generation Partnership Project (3GPP) to provide IP Multimedia services over 3G mobile communication networks (3GPP TS 23.228 and TS 24.229 Release 5 and Release 6). IMS provides key features to enrich the end-user person-to-person communication experience through the integration and interaction of services. IMS allows new rich person-to-person (client-to-client) as well as person-to-content (client-to-server) communications over an IP-based network. The IMS makes use of the Session Initiation Protocol (SIP) to set up and control calls or sessions between user terminals (or user terminals and web servers). The Session Description Protocol (SDP), carried by SIP signalling, is used to describe and negotiate the media components of the session. Other protocols are used for media transmission and control, such as Real-time Transport Protocol and Real-time Transport Control Protocol (RTP/RTCP), Message Session Relay Protocol (MSRP), Hyper Text Transfer Protocol (HTTP).
The boundaries between the services provided by telecommunication operators, TV operators, and internet service providers are disappearing, and such companies are offering customers all three services (so called “triple play”). For telecommunication operators wishing to offer TV services, a popular choice is to utilize so called IPTV, which delivers a TV service over IP and the customer's broadband connection (e.g. ADSL, VDSL, Public Ethernet, etc.).
With the convergence between IPTV services and the IMS infrastructure, a new range of possibilities opens up for an end user to utilize their TV set. For example, videoconferencing, interactive gaming, personalized advertisement or interactive TV programmes with viewers' feedback are easily achievable using IMS.
In order to be able to view IPTV broadcasts, the end user requires a device that can receive IPTV media, such as a set top box (STB), that may or may not be IMS enabled or have SIP functionality. Means are required to enable the establishment of an RTP media session, such as an IPTV media session, from the IMS network to a device such as a STB for displaying the RTP media content.